1. Field of the Invention
The present invention relates to an image processing apparatus for processing moving images, a method of the same, and a program and a storage medium of the same.
2. Description of the Art
Computer graphics (CG) technology is widely used in games, movies, advertisements, TV, etc. CG rendering is a technique for mapping CG data existing in a virtual three-dimensional space on a virtual screen for display. The main CG rendering techniques includes the Z-buffer method, the scanline method, the raytracing method, the radiocity method, etc.
For example the raytracing method designates an object nearest the eye in CG data existing on an extension of a straight line (ray) heading from the eye toward a pixel on a screen as the result of rendering. Further, by setting a reflectance, transmittance, refractive index, etc. in the CG data, retracing light from an intersection of a line of sight and the object, and reflexively repeating the reflection and refraction, a transparent object, a reflecting object, etc. can be simulated. Therefore, there is the characteristic that a high quality rendering result can be prepared. On the other hand, the raytracing method had the problem that when reflection, refraction, and other processing increased, the rays branched, therefore the processing became enormous. In particular, when producing CG animation, the rendering time is a big problem, so the bounding volume method, the space division method, and other techniques for increasing the speed have been developed.
These speed-increasing techniques mainly speed up the calculation of the intersection of a ray running from the eye through each pixel with an object on three-dimensional coordinates.
The bounding volume method is a technique of covering a rendering object having a complex shape requiring a long time for intersection judgment by an object enabling intersection judgment at a high speed, for example, a cube, and performing the intersection judgment with respect to that object in advance.
The space division method divides a three-dimensional space into box cells and advance and registers which object belongs to each box cell. This technique sequentially inspects only the box cells through which a ray passes from the one nearest the start point of the ray and performs detailed intersection judgment only for objects registered in those box cells, thereby increases the speed.
Further, as a speed-increasing technique on a two-dimensional plane, the method is known of having the user designate regions required at the time of a final output in a rendered image while viewing a preview and rendering only the designated regions at the time of the main rendering so as to eliminate unused useless rendering parts and increase the speed.
As specific related art, there is Japanese Patent Publication (A) No. 2000-20746.
Summarizing the issue to be handled in the present invention, the conventional speed-increasing methods are speed-increasing techniques in three-dimensional space. The main methods rely on the rendering technique. For example, it was not possible to utilize the speed-increasing technique of intersection judgment of a ray by the bounding volume method as is for the scanline method. The user had to previously designate the regions to be rendered. Further, the rendering time of the regions to be rendered was not reduced. In addition, for high quality rendering with a high frame rate, a large calculation power is necessary, so a further increase in the speed of algorithms has been desired.